<template>
  <div>
    <h3>我是子组件</h3>
    <h4>{{ value123 }}</h4>
    <button @click="btnClick">修改value</button>
  </div>
</template>
<script>
export default {
  props: {
    value123: {
      type: Number,
      required: true
    }
  },
  model: {
    prop: 'value123',
    event: 'input123'
  },
  methods: {
    btnClick () {
      this.$emit('input123', this.value123 + 1)
    }
  }
}
</script>
<style></style>
